1. Field of the Invention
This invention relates to filters for cigarettes. In one aspect it relates to a filter with novel ventilating means therein. In another respect, the invention relates to a filter cigarette wherein the ventilating air and smoke exiting the filter are in separate streams.
2. Description of the Prior Art
It is well known in the art of filters for cigarettes to utilize ambient air for the dilution of the cigarette smoke prior to entering the smoker's mouth. The dilution of the smoke stream reduces the quantity of smoke particulates as well as gas phase components which are delivered to the mouth of the smoker. A number of means have been proposed and are utilized for introducing ventilating air into the cigarette. For example, the wrapper for the tobacco column may be made from a porous material which allows for introduction of air along the entire length of the cigarette thereby mixing and diluting the smoke stream as it passes therethrough. Also, the cigarette wrapper may be perforated at selected locations along the length of the cigarette to provide ports through which ventilating air enters the cigarette. Even further, it is known to perforate the wrapper of a filter on the end of a cigarette to allow for ventilating air to enter the filter for dilution of the smoke stream in the filter. Recently it has been proposed to make filters for cigarettes wherein the ventilating air and the smoke stream passing through the filter are in separate streams and do not mix until they exit the filter. These include U.S. Pat. No. 3,324,862; U.S. Pat. No. 3,390,684; U.S. Pat. No. 3,490,461; U.S. Pat. No. 4,023,576; U.S. Pat. No. 4,256,122; and, German Pat. No. 2,849,904.